Monitoring light output from at least one solid-state light source

ABSTRACT

A method of monitoring light output from at least one solid-state light source involves sensing any light produced by the at least one solid-state light source and reflected, by at least one surface spaced apart from the at least one solid-state light source, to at least one reference location spaced apart from the at least one surface. Apparatuses and uses of the apparatuses are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of, and priority to, Canadian patentapplication no. 2,980,361 filed Sep. 25, 2017, the entire contents ofwhich are incorporated by reference herein.

FIELD

This disclosure relates generally to monitoring light output from atleast one solid-state light source.

RELATED ART

Fluids, such as water or air for example, may be treated, for example todeactivate pathogens, by subjecting the fluid to UV light, andsolid-state light sources such as light-emitting diodes (“LEDs”) mayproduce such UV light. However, LEDs can fail or become less effective,either of which may go unnoticed. As a result, fluid may unknowingly notbe treated or may be inadequately treated, which can result, forexample, in health hazards. For instance, pathogens may not besufficiently deactivated, if LEDs fail or become less effective in afluid treatment apparatus.

SUMMARY

In accordance with one illustrative embodiment of the invention, thereis provided a method of monitoring light output from at least onesolid-state light source. The method may include sensing any lightproduced by the at least one solid-state light source and reflected, byat least one surface spaced apart from the at least one solid-statelight source, to at least one reference location spaced apart from theat least one surface.

The method may further include producing at least one sensor signalrepresenting sensing light produced by the at least one solid-statelight source and reflected by the at least one surface to the at leastone reference location.

Sensing may include sensing no light produced by the at least onesolid-state light source and reflected by the at least one surface tothe at least one reference location.

The method may include producing at least one sensor signal representingsensing no light produced by the at least one solid-state light sourceand reflected by the at least one surface to the at least one referencelocation.

The method may further include producing at least one error signal inresponse to the sensor signal representing sensing no light produced bythe at least one solid-state light source and reflected by the at leastone surface to the at least one reference location.

The method may further include producing at least one error signal inresponse to the sensor signal representing sensing no light produced bythe at least one solid-state light source and reflected by the at leastone surface to the at least one reference location when an electricpotential is applied across the at least one solid-state light source tocause the at least one solid-state light source to produce light.

Sensing may comprise sensing a level of light produced by the at leastone solid-state light source and reflected by the at least one surfaceto the at least one reference location.

The method may further include producing at least one sensor signalrepresenting the level of light.

The method may further include producing at least one error signal inresponse to the sensor signal representing sensing the level of lightbelow a threshold level.

The method may further include producing at least one error signal inresponse to the sensor signal representing sensing the level of lightbelow a threshold level when an electric potential is applied across theat least one solid-state light source to cause the at least onesolid-state light source to produce light.

Sensing any light produced by the at least one solid-state light sourceand reflected by the at least one surface may include sensing anyultraviolet (“UV”) light produced by the at least one solid-state lightsource and reflected by the at least one surface.

The at least one solid-state light source may be a single solid-statelight source.

The at least one reference location may be a single reference location.

The at least one reference location may be outside of an entire spacebetween the at least one solid-state light source and at least onetranslucent body positioned to transmit a portion of any light producedby the at least one solid-state light source.

The at least one surface may include at least one surface of the atleast one translucent body, and sensing any light produced by the atleast one solid-state light source and reflected by the at least onesurface to the at least one reference location may include sensing anylight produced by the at least one solid-state light source andreflected by the at least one surface of the at least one translucentbody to the at least one reference location.

The at least one surface may include at least one surface of at leastone translucent body positioned to transmit a portion of any lightproduced by the at least one solid-state light source, and sensing anylight produced by the at least one solid-state light source andreflected by the at least one surface to the at least one referencelocation may include sensing any light produced by the at least onesolid-state light source and reflected by the at least one surface ofthe at least one translucent body to the at least one referencelocation.

The at least one translucent body may include at least one lens.

The at least one translucent body may include at least one window.

The at least one surface may include at least one reflective surface ofat least one reflective body, and sensing any light produced by the atleast one solid-state light source and reflected by the at least onesurface to the at least one reference location may include sensing anylight produced by the at least one solid-state light source andreflected by the at least one reflective surface of the at least onereflective body to the at least one reference location.

The at least one surface may include at least one reflective surface ofat least one opaque body, and sensing any light produced by the at leastone solid-state light source and reflected by the at least one surfaceto the at least one reference location may include sensing any lightproduced by the at least one solid-state light source and reflected bythe at least one reflective surface of the at least one opaque body tothe at least one reference location.

The at least one surface may include at least one surface of an opticalhead including the at least one solid-state light source and the atleast one reference location.

The light reflected by the at least one surface may include lightreflected by the at least one surface by specular reflection.

The light reflected by the at least one surface may include lightreflected by the at least one surface by diffuse reflection.

The at least one solid-state light source and the at least one referencelocation may be on a same device.

The at least one solid-state light source and the at least one referencelocation may be on a same printed circuit board (“PCB”).

The at least one solid-state light source may include at least onelight-emitting diode (“LED”).

In accordance with a further illustrative embodiment of the invention,there is provided a method of treating a fluid. The method may includemonitoring light output from the at least one solid-state light sourcewhen the fluid is in a reaction chamber and positioned to receive lightfrom the at least one solid-state light source.

The at least one surface may include at least one surface of thereaction chamber.

In accordance with a further illustrative embodiment of the invention,there is provided an apparatus for producing light output and formonitoring light output from the apparatus. The apparatus may include:at least one solid-state light source; and a sensing means for sensingany light produced by the at least one solid-state light source andreflected, by at least one surface spaced apart from the at least onesolid-state light source, to at least one reference location spacedapart from the at least one surface.

The apparatus may further include a means for producing at least oneerror signal in response to the sensing means sensing no light producedby the at least one solid-state light source and reflected by the atleast one surface to the at least one reference location.

The apparatus may further include a means for producing at least oneerror signal in response to the sensing means sensing no light producedby the at least one solid-state light source and reflected by the atleast one surface to the at least one reference location when anelectric potential is applied across the at least one solid-state lightsource to cause the at least one solid-state light source to producelight.

The apparatus may further include a means for producing at least oneerror signal in response to the sensing means sensing the level of lightbelow a threshold level.

The apparatus may further include a means for producing at least oneerror signal in response to the sensing means sensing the level of lightbelow a threshold level when an electric potential is applied across theat least one solid-state light source to cause the at least onesolid-state light source to produce light.

The at least one solid-state light source may be operable to produce UVlight, and the sensing means may sense any UV light produced by the atleast one solid-state light source and reflected by at least one surfaceto the at least one reference location.

The apparatus may further include a means for reflecting any lightproduced by the at least one solid-state light source to the at leastone reference location.

In accordance with a further illustrative embodiment of the invention,there is provided an apparatus for producing light output and formonitoring light output from the apparatus. The apparatus may include:at least one solid-state light source; and at least one light sensorpositioned to sense any light produced by the at least one solid-statelight source and reflected, by at least one surface spaced apart fromthe at least one solid-state light source, to at least one referencelocation spaced apart from the at least one surface.

The at least one light sensor may be operable to produce at least onesensor signal representing any light produced by the at least onesolid-state light source and reflected by the at least one surface tothe at least one reference location.

The apparatus may further include circuitry operable to produce at leastone error signal in response to the sensor signal.

The circuitry may be operable to produce the at least one error signalin response to the sensor signal representing sensing no light producedby the at least one solid-state light source and reflected by the atleast one surface to the at least one reference location.

The circuitry may be operable to produce the at least one error signalin response to the sensor signal representing sensing no light producedby the at least one solid-state light source and reflected by the atleast one surface to the at least one reference location when anelectric potential is applied across the at least one solid-state lightsource to cause the at least one solid-state light source to producelight.

The circuitry may be operable to produce the at least one error signalin response to the sensor signal representing sensing the level of lightbelow a threshold level.

The circuitry may be operable to produce the at least one error signalin response to the sensor signal representing sensing the level of lightbelow a threshold level when an electric potential is applied across theat least one solid-state light source to cause the at least onesolid-state light source to produce light.

The at least one solid-state light source may be operable to produce UVlight, and wherein the at least one light sensor is senses any UV lightproduced by the at least one solid-state light source and reflected byat least one surface to the at least one reference location.

The at least one light sensor may be a single light sensor.

The at least one solid-state light source may be a single solid-statelight source.

The at least one reference location may be a single reference location.

The apparatus may further include at least one translucent bodypositioned to transmit a portion of any light produced by the at leastone solid-state light source.

The at least one reference location may be outside of an entire spacebetween the at least one solid-state light source and the at least onetranslucent body.

The at least one surface may include at least one surface of the atleast one translucent body, and the at least one reference location maybe positioned to receive at least some of any light produced by the atleast one solid-state light source and reflected by the at least onesurface of the at least one translucent body to the at least onereference location.

The at least one translucent body may include at least one lens.

The at least one translucent body may include at least one window.

The apparatus may further include at least one reflective body, the atleast one surface may include at least one reflective surface of the atleast one reflective body, and the at least one reference location maybe positioned to receive at least some of any light produced by the atleast one solid-state light source and reflected by the at least onereflective surface of the at least one reflective body to the at leastone reference location.

The at least one reflective surface of the at least one reflective bodymay reflect any light produced by the at least one solid-state lightsource to the at least one reference location by specular reflection.

The at least one reflective surface of the at least one reflective bodymay reflect any light produced by the at least one solid-state lightsource to the at least one reference location by diffuse reflection.

The apparatus may further include at least one opaque body, the at leastone surface may include at least one reflective surface of the at leastone opaque body, and the at least one reference location may bepositioned to receive at least some of any light produced by the atleast one solid-state light source and reflected by the at least onereflective surface of the at least one opaque body to the at least onereference location.

The at least one reflective surface of the at least one opaque body mayreflect any light produced by the at least one solid-state light sourceto the at least one reference location by specular reflection.

The at least one reflective surface of the at least one opaque body mayreflect any light produced by the at least one solid-state light sourceto the at least one reference location by diffuse reflection.

The apparatus may further include an optical head comprising the atleast one solid-state light source and the at least one referencelocation, the at least one surface may include at least one surface ofthe optical head.

The at least one solid-state light source and the at least one referencelocation may be on a same device.

The apparatus may further include a PCB, and the at least onesolid-state light source and the at least one reference location may beon the PCB.

The at least one solid-state light source may include at least one LED.

The apparatus may further include a reaction chamber positioned toreceive light from the at least one solid-state light source.

The reaction chamber may include a fluid conduit.

The at least one surface may include at least one surface of thereaction chamber.

In accordance with a further illustrative embodiment of the invention,there is provided a method of treating a fluid in the reaction chamber.The method may include subjecting the fluid to light from the at leastone solid-state light source.

In various embodiments the fluid may include air. In other embodimentsthe fluid may include water.

Other aspects and features will become apparent to those ordinarilyskilled in the art upon review of the following description ofillustrative embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an apparatus according to oneembodiment.

FIG. 2 is a side view of a window of the apparatus of FIG. 1.

FIG. 3 is a schematic illustration of circuitry of the apparatus of FIG.1.

FIG. 4 is a cross-sectional view of an apparatus according to anotherembodiment.

FIG. 5 is a cross-sectional view of an apparatus according to anotherembodiment.

FIG. 6 is a cross-sectional view of an apparatus according to anotherembodiment.

FIG. 7 is a cross-sectional view of an apparatus according to anotherembodiment.

FIG. 8 is a cross-sectional view of an apparatus according to anotherembodiment.

FIG. 9 is a plan view of an apparatus according to another embodiment.

FIG. 10 is a plan view of an apparatus according to another embodiment.

FIG. 11 is a plan view of an apparatus according to another embodiment.

FIG. 12 is a cross-sectional view of an apparatus according to anotherembodiment.

FIG. 13 is a cross-sectional view of an apparatus according to anotherembodiment.

FIG. 14 is a cross-sectional view of an apparatus according to anotherembodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, an apparatus according to one embodiment is showngenerally at 100 and includes an optical head 102. The optical head 102includes a printed circuit board (“PCB”) 104, which includes alight-emitting diode (“LED”) 106 and a light sensor 108. The LED 106 andthe light sensor 108 are therefore on a same PCB and on a same device,which may allow the optical head 102 to occupy a relatively smallfootprint. The light sensor 108 senses light received at a referencelocation shown generally at 110 and proximate the light sensor 108. Theoptical head 102 also includes a window 112 having an inner surface 114and an outer surface 116 opposite the inner surface 114. Windows such asthose described herein may be made of quartz, fused silica, sapphire,calcium fluoride, and/or magnesium fluoride, for example.

In the embodiment shown, the LED 106 and the light sensor 108 face theinner surface 114 of the window 112, and the window 112 is within anoutput field or view angle shown generally at 118 of the LED 106. As aresult, the window 112 is positioned to receive at least a portion oflight produced by the LED 106 at the inner surface 114. However,alternative embodiments may differ. For example, alternative embodimentsmay omit the PCB 104 or may include alternatives to PCB 104, and inalternative embodiments the LED 106 and the light sensor 108 a differentbut same device. Further, alternative embodiments may includealternatives to the LED 106, which may include other solid-state lightsources, for example. Further, alternative embodiments may includealternatives to the window 112, which may include one or more differentwindows, one or more lenses and/or one or more other optical components,or one or more other translucent bodies. Herein, a “translucent body”includes a “transparent body” and in various embodiments includes anybody that transmits and/or diffuses some or all light received by thebody. Further, alternative embodiments may include more than one LED,more than one light sensor, and/or one or more LEDs and one or morelight sensors that may be positioned differently from the positionsshown in FIG. 1. For example, one or more light sensors may bepositioned to receive a desired amount or type of reflection from atleast one solid-state light source.

In the embodiment shown, the LED 106 produces ultraviolet (“UV”) light,the light sensor 108 senses UV light, and the window 112 is transparentto UV light. Therefore, “light” herein is not limited to visible light,but rather may include other electromagnetic radiation that may notnecessarily be visible. Further, in the embodiment shown, the window 112is positioned to transmit at least a portion of light produced by theLED 106 and received at the inner surface 114. However, alternativeembodiments may differ. For example, in alternative embodiments, the LED106 may produce light that is not necessarily UV light, the light sensor108 may sense any such light produced by the LED 106, and the window 112may be transparent to any such light produced by the LED 106.

Referring to FIG. 2, when light is received at the inner surface 114 ofthe window 112, a portion (shown at 113) of such light may be absorbedby the window 112, a portion (shown at 115) of such light may betransmitted (or refracted and transmitted) by the window 112, and aportion (shown at 117) of such light may be reflected by the window 112.Referring back to FIG. 1, at least a portion of light reflected by thewindow 112 may be received at the reference location 110 and sensed bythe light sensor 108.

The LED 106 and the window 112 define a space or region shown generallyat 120 between the LED 106 and the window 112 and through which space orregion 120 light transmitted by the LED 106 travels to the window 112.The light sensor 108 may be positioned entirely outside of the space orregion 120. As a result, the light sensor 108 may be positioned to avoidblocking any light that may be transmitted from the LED 106 to thewindow 112.

Referring to FIG. 3, the apparatus 100 further includes circuitry showngenerally at 122 including an amplifier 124, an analog-to-digitalconverter (“ADC”) 126, and a controller 128. In the embodiment shown,the light sensor 108 produces an analog sensor signal 130 representing alevel (such as an intensity or power level, for example) of lightproduced by the LED 106 and reflected by the inner surface 114 to thereference location 110. Also, in the embodiment shown, the amplifier 124amplifies the analog sensor signal 130 to produce an amplified analogsensor signal 132, the ADC 126 converts the amplified analog sensorsignal 132 to a digital sensor signal 134, and the controller 128receives the digital sensor signal 134. The controller 128 may include aprocessor circuit including a microprocessor that may be programmed tofunction as described herein, for example.

The circuitry 122 shown is an example only, and alternative embodimentsmay include different circuitry. For example, the light sensor 108 mayproduce one or more analog and/or digital sensor signals that mayrepresent, for example, sensing light produced by the LED 106 andreflected by the inner surface 114 to the reference location 110,sensing no light produced by the LED 106 and reflected by the innersurface 114 to the reference location 110, and/or a level (such as anintensity or power level, for example) of light produced by the LED 106and reflected by the inner surface 114 to the reference location 110.Further, the amplifier 124 and/or the ADC 126 may be omitted or varied,and the controller 128 may include one or more processor circuits, oneor more discrete logic circuits, and/or one or more application-specificintegrated circuits (“ASICs”), for example.

The circuitry 122 may produce an error signal if one or more conditionsare satisfied. For example, in some embodiments, the circuitry 122 mayproduce an error signal if the light sensor 108 senses no light producedby the LED 106 and reflected by the inner surface 114 to the referencelocation 110. Also, in some embodiments, the circuitry 122 may producean error signal if the light sensor 108 senses no light produced by theLED 106 and reflected by the inner surface 114 to the reference location110 when an electric potential is applied across the LED 106 to causethe LED 106 to produce light. Also, in some embodiments, the circuitry122 may produce an error signal if the light sensor 108 senses a levelof light produced by the LED 106 and reflected by the inner surface 114to the reference location 110 that is below a threshold level. Also, insome embodiments, the circuitry 122 may produce an error signal if thelight sensor 108 senses a level of light produced by the LED 106 andreflected by the inner surface 114 to the reference location 110 that isbelow a threshold level when an electric potential is applied across theLED 106 to cause the LED 106 to produce light.

The apparatus 100 shown is an example only, and alternative embodimentsmay vary. For example, referring to FIG. 4, an apparatus according toanother embodiment is shown generally at 136 and includes an opticalhead 138. The optical head 138 includes a PCB 140, which includes an LED142 and a light sensor 144. The light sensor 144 senses light receivedat a reference location shown generally at 146 and proximate the lightsensor 144. The optical head 138 also includes a first lens 148, asecond lens 150, and a window 152. In various embodiments, lenses mayinclude one or more of plano-convex, ball and half-ball, cylindricaland/or concave lenses, or other types of lenses, for example. Further,lenses or other optical components such as those described herein may bemade of quartz, fused silica, sapphire, calcium fluoride, and/ormagnesium fluoride, for example.

As with the apparatus 100, the LED 142 may produce ultraviolet (“UV”)light, the light sensor 144 may sense UV light, and the first lens 148,the second lens 150, and the window 152 may be transparent to UV light,but alternative embodiments may differ and may for example function asdescribed above with light that is not necessarily UV light. Light fromthe LED 142 may be reflected by one or more surfaces of the first lens148, by one or more surfaces of the second lens 150, and/or by one ormore surfaces of the window 152 to the reference location 146. Forexample, light shown at 149 from the LED 142 may be reflected by asurface of the first lens 148 to the reference location 146. As anotherexample, light shown at 151 and 153 may be reflected by a surface of thesecond lens 150 and then refracted and/or transmitted by the first lens148 to the reference location 146. Otherwise the apparatus 136 mayfunction similarly to the apparatus 100 as described above, for example.

As another example, referring to FIG. 5, an apparatus according toanother embodiment is shown generally at 154 includes an optical head156. The optical head 156 includes a PCB 158, which includes an LED 160and a light sensor 162. The light sensor 162 senses light received at areference location shown generally at 164 and proximate the light sensor162. The optical head 156 also includes a window 166 having an innersurface 168. The optical head 156 also includes a housing 170 that mayinclude reflective and/or opaque bodies and that has inner surfaces,such as an inner surface 172 adjacent the window 166 and an innersurface 174 perpendicular to the inner surface 172. The inner surfaces172 and 174 may be reflective surfaces that may reflect light from theLED 160, and the inner surfaces 172 and 174 may reflect light from theLED 160 by specular reflection and/or by diffuse reflection. In general,such additional reflective surfaces may increase light reflected to thelight sensor 162 and increase sensitivity of the light sensor 162.

As with the apparatus 100, the LED 160 may produce UV light, the lightsensor 162 may sense UV light, and the first lens 148, the second lens150, the window 166 may be transparent to UV light, and the innersurfaces 172 and 174 may reflect UV light, but alternative embodimentsmay differ and may for example function as described above with lightthat is not necessarily UV light. Light from the LED 160 may bereflected by the inner surface 168, by the inner surface 172, and/or bythe inner surface 174 to the reference location 164, and otherwise theapparatus 154 may function similarly to the apparatus 100 as describedabove, for example.

As another example, referring to FIG. 6, an apparatus according toanother embodiment is shown generally at 176 and includes an opticalhead 178. The optical head 178 includes a PCB 180, which includes an LED182 and a UV sensor 184. The apparatus 176 is similar to the apparatus100 except that the apparatus 176 includes an optical lens 186 (whichmay be a half-ball, a dome lens, or a converging lens, for example) onthe UV sensor 184. In general, such an optical lens 186 may collectreflected light and may increase reflected light directed to the UVsensor 184 and increase sensitivity of the UV sensor 184. FIG. 6illustrates a quartz window 188, although alternative embodiments mayinclude one or more different translucent bodies. Further, although FIG.6 illustrates a UV sensor 184, alternative embodiments may includedifferent light sensors.

As another example, referring to FIG. 7, an apparatus according toanother embodiment is shown generally at 190 and includes a PCB 192including an LED 194 and a UV sensor 196. The apparatus 190 alsoincludes a reflective surface 198 and an optical lens 200, and issimilar to the apparatus 100. Although FIG. 7 illustrates one opticallens 200, alternative embodiments may include one or more differenttranslucent bodies. Further, although FIG. 7 illustrates a UV sensor196, alternative embodiments may include different light sensors.

As another example, referring to FIG. 8, an apparatus according toanother embodiment is shown generally at 232 and includes a PCB 234including an LED 236 and a UV sensor 238. The apparatus 232 alsoincludes a reflective surface 240 and an optical lens 242, and issimilar to the apparatus 100. Although FIG. 8 illustrates one opticallens 242, alternative embodiments may include one or more differenttranslucent bodies. Further, although FIG. 8 illustrates a UV sensor238, alternative embodiments may include different light sensors.

The embodiments described above each include one LED, but alternativeembodiments may include more than one LED. For example, referring toFIG. 9, an apparatus according to another embodiment is shown generallyat 202 and includes three LEDs 204, 206, and 208 and one light sensor210. The light sensor 210 may sense, at a reference location proximatethe light sensor 210, any light produced by one or more of the LEDs 204,206, and 208 and reflected by at least one surface spaced apart from theat least one solid-state light source and from the reference location.As a result, the apparatus 202 may monitor light output from the LEDs204, 206, and 208 collectively, and more generally, the apparatus 202may monitor collective light output from more than one light source. Ofcourse, alternative embodiments may differ. For example, alternativeembodiments may include fewer or more than three LEDs that may bepositioned differently from the positions shown in FIG. 9.

As another example, referring to FIG. 10, an apparatus according toanother embodiment is shown generally at 212 and includes three LEDs214, 216, and 218. A light sensor 220 is positioned to sense, at areference location proximate the light sensor 220, any light produced bythe LED 214 and reflected by at least one surface spaced apart from theat least one solid-state light source and from the reference locationproximate the light sensor 220. Further, a light sensor 222 ispositioned to sense, at a reference location proximate the light sensor222, any light produced by the LED 216 and reflected by at least onesurface spaced apart from the at least one solid-state light source andfrom the reference location proximate the light sensor 222. Further, alight sensor 224 is positioned to sense, at a reference locationproximate the light sensor 224, any light produced by the LED 218 andreflected by at least one surface spaced apart from the at least onesolid-state light source and from the reference location proximate thelight sensor 224. Further, an opaque body 226 optically isolates the LED214 and the light sensor 220 from the LED 216 and 222, an opaque body228 optically isolates the LED 216 and the light sensor 222 from the LED218 and the light sensor 224, and an opaque body 230 optically isolatesthe LED 218 and the light sensor 224 from the LED 214 and the lightsensor 220. As a result, the apparatus 212 may monitor light output fromthe LEDs 214, 216, and 218 independently. More generally, the apparatus212 includes light sources associated with respective different lightsensors and may therefore monitor light output from more than one lightsource independently.

However, alternative embodiments may differ. For example, someembodiments may omit some or all of the opaque bodies 226, 228, and 230,or one or more opaque bodies may differ in alternative embodiments. Asanother example, alternative embodiments may include fewer or more thanthree LEDs and fewer or more than three light sensors, and LEDs andlight sensors according to alternative embodiments may be positioneddifferently from the positions shown in FIG. 10.

As another example, referring to FIG. 11, an apparatus according toanother embodiment is shown generally at 256, is similar to theapparatus 100, 136, or 154, for example, and includes a PCB 258, a lightsensor (or UV sensor) 260, and an LED (or UV-LED) 262.

The embodiments described above are examples only, and embodimentsdescribed above may be varied or combined with other embodiments in manyways. For example, alternative embodiments may include alternatives toLEDs, which may include other solid-state light sources, for example.Also, the reflective surfaces of the embodiments described above areexamples only, and alternative embodiments may omit such reflectivesurfaces, or alternative embodiments may include reflective surfacesthat may be positioned, angled, and/or shaped differently from those ofthe embodiments described above. Further, the translucent bodiesdescribed above are examples only, and alternative embodiments mayinclude omit such translucent bodies or may include one or moretranslucent bodies that may be similar to or different from thetranslucent bodies of the embodiments described above. For example,reflective surfaces and/or translucent bodies such as windows, lenses,or other optical components may be positioned, angled, coated (forexample with one or more UV-reflective, UV-anti-reflective,light-reflective, and/or light-anti-reflective coatings, for example),treated, and/or shaped to obtain a desired amount or type of reflectionfrom at least one solid-state light source to at least one referencelocation, to obtain a desired refraction-to-reflection radiation ratio,and/or more generally to obtain desired sensor performance.

Referring to FIG. 12, an apparatus according to another embodiment isshown generally at 244 and includes an optical head 246 (which may besimilar to one of the optical heads described above, for example)including a PCB 248 including an LED 250. The apparatus 244 alsoincludes a reaction chamber 252 positioned to receive light from the LED250 of the optical head 246 through a UV-transparent window 254.Therefore, in some embodiments, one or more translucent bodies (such asthe UV-transparent window 254, for example) may be an interface betweenan optical head (such as the optical head 246 or one of the otheroptical heads described above, for example) and a reaction chamber (suchas the reaction chamber 252, for example) of a photo-reactor. In someembodiments, the reaction chamber may include a fluid conduit.

Referring to FIG. 13, an apparatus according to another embodiment isshown generally at 264 and includes an optical head 266 (which may besimilar to one of the optical heads described above, for example)including a PCB 268 including an LED 270 and a light sensor 272. Theapparatus 264 also includes a reaction chamber 274 positioned to receivelight from the LED 270 of the optical head 266 through a UV-transparentwindow 276. One or more internal surfaces of the reaction chamber 274may be reflective to light (such as UV light, for example), and as shownin FIG. 13, at least a portion of light reflected by one or moreinternal surfaces of the reaction chamber 274 may be sensed by the lightsensor 272.

Referring to FIG. 14, an apparatus according to another embodiment isshown generally at 278 and includes an optical head 280 (which may besimilar to one of the optical heads described above, for example)including a PCB 282 including an LED 284 and a light sensor 286. Theapparatus 278 also includes a reaction chamber 288 positioned to receivelight from the LED 284 of the optical head 280 through a UV-transparentwindow 290. One or more internal surfaces of the reaction chamber 288may be reflective to light (such as UV light, for example), and as shownin FIG. 14, at least a portion of light reflected by one or moreinternal surfaces of the reaction chamber 288 may be sensed by the lightsensor 286. Further, at least a portion of light reflected by theUV-transparent window 290 may be sensed by the light sensor 286.

As shown in embodiments as described above, for example, light sensorssuch as those described herein may sense reflected light from one ormore transparent bodies (such as one or more lenses and/or one or morewindows) and/or from one or more reflective surfaces (which may includeone or more surfaces of a reactor head, one or more surfaces of areaction chamber, and/or one or more other surfaces).

In general, apparatuses such as those described above may include one ormore reaction chambers and/or one or more fluid conduits, and opticalheads such as those described above may be positioned such that one ormore reaction chambers and/or one or more fluid conduits may bepositioned to receive light from LEDs such as those described above.Therefore, fluid (such as air and/or water, for example) in one or morereaction chambers and/or one or more fluid conduits may receive or besubjected to light from LEDs such as those described above, and suchfluid may be treated by subjecting such fluid to such light, which mayinclude UV light for example.

In general, embodiments such as those described herein may include orcooperate with one or more photo-reactors, such as fluid treatmentapparatuses for example, and monitor light output from at least onesolid-state light source such as at least one LED, and embodiments suchas those described herein may include apparatuses for producing lightoutput and for monitoring light output from such apparatuses. Forexample, embodiments such as those described herein may monitorreflected light, which may otherwise have been wasted. Further,embodiments such as those described herein may produce one or more errorsignals, which may indicate that one or more LEDs have failed is/arefailing, and which may prevent unknowingly failing to treat air and/orwater in one or more fluid treatment apparatuses. Further, light sensorssuch as those described herein may be positioned entirely outside of anentire space (such as the space 120, for example) between at least onesolid-state light source and at least one translucent body positioned totransmit a portion of any light produced by the at least one solid-statelight source, which may avoid blocking any light that may be transmittedfrom the at least one solid-state light source to the at least onetranslucent body, and which may increase performance of a photo-reactorwhen compared to a photo-reactor in which a light sensor may block lightthat may be transmitted from at least one solid-state light source to atleast one translucent body.

Although specific embodiments have been described and illustrated, suchembodiments should be considered illustrative only and not as limitingthe invention as construed according to the accompanying claims.

The invention claimed is:
 1. A fluid treatment apparatus comprising: atleast one solid-state electromagnetic radiation source; a reactionchamber positioned to receive electromagnetic radiation from the atleast one solid-state electromagnetic radiation source to subject afluid in the reaction chamber to the electromagnetic radiation; and atleast one electromagnetic radiation sensor positioned to sense anyelectromagnetic radiation produced by the at least one solid-stateelectromagnetic radiation source and reflected, by at least one surfacespaced apart from the at least one solid-state electromagnetic radiationsource, to at least one reference location spaced apart from the atleast one surface.
 2. The apparatus of claim 1 wherein the at least oneelectromagnetic radiation sensor is operable to produce at least onesensor signal representing any electromagnetic radiation produced by theat least one solid-state electromagnetic radiation source and reflectedby the at least one surface to the at least one reference location. 3.The apparatus of claim 2 further comprising circuitry operable toproduce at least one error signal in response to the sensor signalrepresenting sensing no electromagnetic radiation produced by the atleast one solid-state electromagnetic radiation source and reflected bythe at least one surface to the at least one reference location.
 4. Theapparatus of claim 2 further comprising circuitry operable to produce atleast one error signal in response to the sensor signal representingsensing the level of electromagnetic radiation below a threshold level.5. The apparatus of claim 1 wherein the at least one solid-stateelectromagnetic radiation source is operable to produce ultraviolet (UV)electromagnetic radiation, and wherein the at least one electromagneticradiation sensor senses any UV electromagnetic radiation produced by theat least one solid-state electromagnetic radiation source and reflectedby at least one surface to the at least one reference location.
 6. Theapparatus of claim 1 further comprising at least one translucent bodypositioned between the at least one solid-state electromagneticradiation source and the reaction chamber to transmit a portion of anyelectromagnetic radiation produced by the at least one solid-stateelectromagnetic radiation source into the reaction chamber.
 7. Theapparatus of claim 6 wherein the at least one reference location isoutside of an entire space between the at least one solid-stateelectromagnetic radiation source and the at least one translucent body.8. The apparatus of claim 6 wherein the at least one surface comprisesat least one surface of the at least one translucent body, and whereinthe at least one reference location is positioned to receive at leastsome of any electromagnetic radiation produced by the at least onesolid-state electromagnetic radiation source and reflected by the atleast one surface of the at least one translucent body to the at leastone reference location.
 9. The apparatus of claim 1 further comprisingat least one reflective body, wherein the at least one surface comprisesat least one reflective surface of the at least one reflective body, andwherein the at least one reference location is positioned to receive atleast some of any electromagnetic radiation produced by the at least onesolid-state electromagnetic radiation source and reflected by the atleast one reflective surface of the at least one reflective body to theat least one reference location.
 10. The apparatus of claim 9 whereinthe at least one reflective surface of the at least one reflective bodyreflects any electromagnetic radiation produced by the at least onesolid-state electromagnetic radiation source to the at least onereference location by specular reflection.
 11. The apparatus of claim 9wherein the at least one reflective surface of the at least onereflective body reflects any electromagnetic radiation produced by theat least one solid-state electromagnetic radiation source to the atleast one reference location by diffuse reflection.
 12. The apparatus ofclaim 1 further comprising at least one opaque body, wherein the atleast one surface comprises at least one reflective surface of the atleast one opaque body, and wherein the at least one reference locationis positioned to receive at least some of any electromagnetic radiationproduced by the at least one solid-state electromagnetic radiationsource and reflected by the at least one reflective surface of the atleast one opaque body to the at least one reference location.
 13. Theapparatus of claim 1 further comprising an optical head comprising theat least one solid-state electromagnetic radiation source and the atleast one reference location, wherein the at least one surface comprisesat least one surface of the optical head.
 14. The apparatus of claim 1wherein the at least one solid-state electromagnetic radiation sourceand the at least one reference location are on a same device.
 15. Theapparatus of claim 1 further comprising a printed circuit board (PCB),wherein the at least one solid-state electromagnetic radiation sourceand the at least one reference location are on the PCB.
 16. Theapparatus of claim 1 wherein the reaction chamber comprises a fluidconduit.
 17. The apparatus of claim 1 wherein the at least one surfacecomprises at least one surface of the reaction chamber.
 18. A method oftreating a fluid in the reaction chamber of the apparatus of claim 1,the method comprising: subjecting the fluid to electromagnetic radiationfrom the at least one solid-state electromagnetic radiation source. 19.The method of claim 18 wherein the fluid comprises water.
 20. Theapparatus of claim 1 further comprising an optical head comprising theat least one solid-state electromagnetic radiation source and the atleast one reference location, wherein the at least one solid-stateelectromagnetic radiation source and the at least one electromagneticradiation sensor are in a same compartment of the optical head.